[scaladoc] fix: Only trim one newline when preprocessing the content of a markdown code snippet

scaladoc-testcases/docs/_docs/index.md

@@ -13,5 +13,12 @@ class Renderer(using RenderingContext)
 val renderer: Renderer = Renderer()
 ```
 
+```scala
+  trait Ord:
+    type Self
 
+  trait SemiGroup:
+    type Self
+    extension (x: Self) def combine(y: Self): Self
+```
 

scaladoc/src/dotty/tools/scaladoc/renderers/Renderer.scala

@@ -30,71 +30,72 @@ abstract class Renderer(rootPackage: Member, val members: Map[DRI, Member], prot
 
   val rootApiPage: Option[Page] = Some(memberPage(rootPackage)).filter(_.children.nonEmpty).map(_.withTitle(ctx.args.name))
 
-  val rootDocsPage: Option[Page] = staticSite match
-      case None => None
-      case Some(siteContext) =>
-        val rootTemplate = siteContext.staticSiteRoot.rootTemplate
-
-        // Below code is for walking in order the tree and modifing its nodes basing on its neighbours
-
-        // We add dummy guards
-        val notHidden: Seq[Option[LoadedTemplate]] = None +: siteContext.allTemplates.filterNot(_.hidden).map(Some(_)) :+ None
-
-        // Let's gather the list of maps for each template with its in-order neighbours
-        val newSettings: List[Map[String, Object]] = notHidden.sliding(size = 3, step = 1).map {
-          case None :: None :: Nil =>
-            Map.empty
-          case prev :: mid :: next :: Nil =>
-            def link(sibling: Option[LoadedTemplate]): Option[String] =
-              def realPath(path: Path) = if Files.isDirectory(path) then Paths.get(path.toString, "index.html") else path
-              sibling.map { n =>
-                val realMidPath = realPath(mid.get.file.toPath)
-                val realSiblingPath = realPath(n.file.toPath)
-                realMidPath.relativize(realSiblingPath).toString.stripPrefix("../")
-              }
-            List(
-              for {
-                link <- link(prev)
-                p <- prev
-              } yield (
-                "previous" -> Map(
-                  "title" -> p.templateFile.title.name,
-                  "url" -> link
-                )
-              ),
-              for {
-                link <- link(next)
-                n <- next
-              } yield (
-                "next" -> Map(
-                  "title" -> n.templateFile.title.name,
-                  "url" -> link
-                )
-              ),
-            ).flatten.toMap
-        }.toList
-
-        def updateSettings(templates: Seq[LoadedTemplate], additionalSettings: ListBuffer[Map[String, Object]]): List[LoadedTemplate] =
-          val updatedTemplates = List.newBuilder[LoadedTemplate]
-          for template <- templates do
-            val head: Map[String, Object] =
-              if template.hidden then Map.empty
-              else additionalSettings.remove(0)
-            val current: Map[String, Object] = template.templateFile.settings.getOrElse("page", Map.empty).asInstanceOf[Map[String, Object]]
-            val updatedTemplateFile = template.templateFile.copy(settings = template.templateFile.settings.updated("page", head ++ current))
-            updatedTemplates += template.copy(
-              templateFile = updatedTemplateFile,
-              children = updateSettings(template.children, additionalSettings)
-            )
-          updatedTemplates.result()
-
-        val newTemplates = updateSettings(Seq(rootTemplate), newSettings.to(ListBuffer))
-        val templatePages = newTemplates.map(templateToPage(_, siteContext))
-
-        val newRoot = newTemplates.head
-
-        Some(newRoot).filter(r => r.children.nonEmpty || r.templateFile.rawCode.nonEmpty)
-          .map(templateToPage(_, siteContext))
+  val rootDocsPage: Option[Page] = staticSite match {
+    case None => None
+    case Some(siteContext) =>
+      val rootTemplate = siteContext.staticSiteRoot.rootTemplate
+
+      // Below code is for walking in order the tree and modifing its nodes basing on its neighbours
+
+      // We add dummy guards
+      val notHidden: Seq[Option[LoadedTemplate]] = None +: siteContext.allTemplates.filterNot(_.hidden).map(Some(_)) :+ None
+
+      // Let's gather the list of maps for each template with its in-order neighbours
+      val newSettings: List[Map[String, Object]] = notHidden.sliding(size = 3, step = 1).map {
+        case None :: None :: Nil =>
+          Map.empty
+        case prev :: mid :: next :: Nil =>
+          def link(sibling: Option[LoadedTemplate]): Option[String] =
+            def realPath(path: Path) = if Files.isDirectory(path) then Paths.get(path.toString, "index.html") else path
+            sibling.map { n =>
+              val realMidPath = realPath(mid.get.file.toPath)
+              val realSiblingPath = realPath(n.file.toPath)
+              realMidPath.relativize(realSiblingPath).toString.stripPrefix("../")
+            }
+          List(
+            for {
+              link <- link(prev)
+              p <- prev
+            } yield (
+              "previous" -> Map(
+                "title" -> p.templateFile.title.name,
+                "url" -> link
+              )
+            ),
+            for {
+              link <- link(next)
+              n <- next
+            } yield (
+              "next" -> Map(
+                "title" -> n.templateFile.title.name,
+                "url" -> link
+              )
+            ),
+          ).flatten.toMap
+      }.toList
+
+      def updateSettings(templates: Seq[LoadedTemplate], additionalSettings: ListBuffer[Map[String, Object]]): List[LoadedTemplate] =
+        val updatedTemplates = List.newBuilder[LoadedTemplate]
+        for template <- templates do
+          val head: Map[String, Object] =
+            if template.hidden then Map.empty
+            else additionalSettings.remove(0)
+          val current: Map[String, Object] = template.templateFile.settings.getOrElse("page", Map.empty).asInstanceOf[Map[String, Object]]
+          val updatedTemplateFile = template.templateFile.copy(settings = template.templateFile.settings.updated("page", head ++ current))
+          updatedTemplates += template.copy(
+            templateFile = updatedTemplateFile,
+            children = updateSettings(template.children, additionalSettings)
+          )
+        updatedTemplates.result()
+
+      val newTemplates = updateSettings(Seq(rootTemplate), newSettings.to(ListBuffer))
+      val templatePages = newTemplates.map(templateToPage(_, siteContext))
+
+      val newRoot = newTemplates.head
+
+      Some(newRoot).filter(r => r.children.nonEmpty || r.templateFile.rawCode.nonEmpty)
+        .map(templateToPage(_, siteContext))
+  }
 
   val redirectPages: Seq[Page] = staticSite.fold(Seq.empty)(siteContext => siteContext.redirectTemplates.map {
     case (template, driFrom, driTo) =>

scaladoc/src/dotty/tools/scaladoc/snippets/FlexmarkSnippetProcessor.scala

@@ -65,7 +65,7 @@ object FlexmarkSnippetProcessor:
             content.add(s, 0)
             node.setContent(content)
 
-        val fullSnippet = Seq(snippetImports, snippet).mkString("\n").trim
+        val fullSnippet = Seq(snippetImports, snippet).mkString("\n").stripPrefix("\n")
         val snippetCompilationResult = cf(fullSnippet, lineOffset, argOverride) match {
           case Some(result @ SnippetCompilationResult(wrapped, _, _, messages)) =>
             node.setContentString(fullSnippet)